Update JS dependencies (#15033)

* Update JS dependencies

- Update all JS dependencies
- For octicons, rename trashcan to trash
- For svgo, migrate to v2 api, output seems to have slightly changed but icons look the same
- For stylelint, update config, fix custom property duplicates
- For monaco, drop legacy Edge support
- For eslint, enable new rules, fix new issues
- For less-loader, remove deprecated import syntax

* update svgo usage in generate-images and rebuild logo.svg with it

public/img/svg/octicon-repo.svg

@@ -1 +1 @@
-<svg viewBox="0 0 16 16" class="svg octicon-repo" width="16" height="16" aria-hidden="true"><path fill-rule="evenodd" d="M2 2.5A2.5 2.5 0 014.5 0h8.75a.75.75 0 01.75.75v12.5a.75.75 0 01-.75.75h-2.5a.75.75 0 110-1.5h1.75v-2h-8a1 1 0 00-.714 1.7.75.75 0 01-1.072 1.05A2.495 2.495 0 012 11.5v-9zm10.5-1V9h-8c-.356 0-.694.074-1 .208V2.5a1 1 0 011-1h8zM5 12.25v3.25a.25.25 0 00.4.2l1.45-1.087a.25.25 0 01.3 0L8.6 15.7a.25.25 0 00.4-.2v-3.25a.25.25 0 00-.25-.25h-3.5a.25.25 0 00-.25.25z"/></svg>
+<svg viewBox="0 0 16 16" class="svg octicon-repo" width="16" height="16" aria-hidden="true"><path fill-rule="evenodd" d="M2 2.5A2.5 2.5 0 0 1 4.5 0h8.75a.75.75 0 0 1 .75.75v12.5a.75.75 0 0 1-.75.75h-2.5a.75.75 0 1 1 0-1.5h1.75v-2h-8a1 1 0 0 0-.714 1.7.75.75 0 0 1-1.072 1.05A2.495 2.495 0 0 1 2 11.5v-9zm10.5-1V9h-8c-.356 0-.694.074-1 .208V2.5a1 1 0 0 1 1-1h8zM5 12.25v3.25a.25.25 0 0 0 .4.2l1.45-1.087a.25.25 0 0 1 .3 0L8.6 15.7a.25.25 0 0 0 .4-.2v-3.25a.25.25 0 0 0-.25-.25h-3.5a.25.25 0 0 0-.25.25z"/></svg>